Are you using burst mode Andy? If you follow the car with burst mode you'll get more waste shots sure but you're more likely to get that one picture that looks awesome
Panning is all about practice, practice, practice. Check your stance as well before shooting and you'll be taking shots at 1/60 and 1/40 in no time. As regards the monopod, some people find they help some find they are restrictive. Its entirely up to you but try shooting with and without the monopod.